Targeting the search for biodiversity with environmental variables

Environment Australia is tasked with managing the networks of Commonwealth Marine Reserves. This is particularly challenging in the remote and poorly known N and NW regions. For example, managers need to understand how biodiversity varies across these regions, but no dataset of this exists. To provide a starting point for building this knowledge, researchers from Australia's NESP Marine Biodiversity Hub's D1 project here highlight five key environmental variables that may help predict biodiversity patterns across the regions.

These variables were identified because continuous datasets of them are available over the entire N and NW regions, and they serve as proxies for other variables that may more directly affect biodiversity. For example, no regional-scale dataset of substrate hardness currently exists, but available datasets of bottom current velocity and geomorphic features help determine substrate hardness patterns.

Click on the name of each environmental variable below to view an interactive map and read more about it. More datasets will be added to the maps as they are uploaded to the NW Atlas.

Environmental variables

Depth is a consistently powerful explanatory variable in benthic studies due to its association with a range of other factors that directly affect abundance, biomass, and biodiversity (e.g. pressure, primary productivity, temperature).

Sediment grain-size is often assumed to be a key driver of infaunal communities. Gravel, sand and mud all have different properties that may affect the species and abundances of infaunal animals present.

Chlorophyll-a can be estimated at continuous broad scales in the top layers of the ocean via satellite imagery. High primary productivity tends to promote low species richness and high evenness due to the ability of a few species to monopolise resources under ambient conditions.

Geomorphic features are categorical descriptors of the shape of the seabed that range in scale from 1000s of km² (e.g. basins) to 10s of m². They themselves do not directly affect biodiversity, but since they are associated with depth, substrate hardness, current velocity, and productivity, they can help link seabed structure to benthic community distribution.

Bottom current velocity can affect benthic abundance and biodiversity by altering disturbance regimes, changing available habitats, and regulating nutrient flows. Highest biodiversity will be generally associated with occasional episodes of strong bottom current velocity, as per the intermediate disturbance hypothesis.